"I saw these three bundles, you know, it looked like maybe $20,000 to $30,000. I didn't know — the whole bag was full," MacCausland told NECN.

When he couldn't find the man, MacCausland took the bag of money to police. The owner of the backpack called police and was able to provide proof of ownership. The man had reportedly just cashed in his inheritance.

The man gave MacCausland a $100 reward and, according to the Boston Globe, the driver won't have to pay rent on his cab this weekend.